1. Field of the Invention
This invention relates to a non-fogging coating composition for the formation of coating films excelling in non-fogging property or proofness against haze and resistance to scratch or to wear as well as weatherability and to shaped articles of polycarbonate type resins coated with the composition mentioned above. More particularly, this invention relates to a non-fogging coating composition excelling in non-fogging property, resistance to scratch and weatherability, and to coated shaped articles of polycarbonate type resins which are produced by forming substrates of polycarbonate type resins, coating the substrates with an undercoat of good adherency to the substrates, allowing the undercoat to set, then applying the non-fogging coating composition mentioned above as an overcoat to the set undercoat and allowing the overcoat to set and which, therefore, combines high resistance to scratch and good non-fogging property.
2. Description of the Prior Arts
The fault found with plastics, inorganic glasses, etc. which heretofore have been used as transparent materials is the fact that when their surface temperature falls below the dew point of the ambient air, their surfaces are fogged and consequently deprived of transparency even to an extent of causing a serious inconvenience. Various studies and experiments, therefore, have been made in search of a method capable of forming a non-fogging coat on the surface of such transparent materials.
It has been known to form such a coat by using a composition made preponderantly of a polymer of a hydroxyethyl methacrylate or polyvinyl alcohol, for example. This and all other non-fogging coating compositions heretofore put to trial are fairly satisfactory in terms of non-fogging property. Nevertheless, they are highly susceptible to injuries and destitute of scratch resistance and weatherability. The disadvantage has prevented them from being put to practical use.
Generally, polycarbonate type resins excel in impact resistance and transparency. They nevertheless have a disadvantage that they offer poor resistance to scratch and the action of solvents and readily sustain injuries on the surface and yield to organic solvents. Moreover, when the resin surface temperature falls below the dew point of the ambient air, the surface is fogged and deprived of transparency at times to an extent of causing no small inconvenience. To remedy the various disadvantages pointed out above, coating methods aimed at forming various coating films on their surface have been studied. None of them, however, have succeeded in providing a coating film which combines high resistance to scratch and non-fogging property and, at the same time, excels in adherency to substrates.
It is, therefore, an object of this invention to provide a coating composition which is capable of forming a coating film possessing non-fogging property and combining scratch resistance and weatherability.
Another object of this invention is to provide shaped articles of coated polycarbonate type resins excelling in resistance to scratch and non-fogging property as well as adherency of the coats to the substrates.
A further object of this invention is to provide a method for the manufacture of coated polycarbonate type resins which excel in resistance to scratch and non-fogging property as well as adherency of the coats to the substrates.